1. Field of the Invention
The present invention relates to a water-absorbent resin. It relates, more particularly, to a starch-or cellulose-based water-absorbent resin.
2. Descritpion of the Prior Art
Heretofore, non-woven fabrics, papers, pulps, spongy urethane resins, natural sponges, and the like have been used as water-absorbing materials for sanitary napkins, diapers, disposable dustcloths for kitchens, etc. However, these materials have low-water-absorbences and have not been sufficiently satisfactory for the above-mentioned purposes. In recent years, substitutes for these materials, such as cross-linked polyethylene oxide, cross-linked polyvinylalcohol and hydrolyzed products of starch-polyacrylonitrile-grafted polymer have appeared on the market. These products, however, still suffer from significant disadvantages in that their water-absorbences, though relatively high are still not sufficiently satisfactory in that they are expensive because of inherent difficulties in their production processes; in that some create problems of disposal because they are not biologically decomposable, etc. Consequently, there still exists a need for a highly water absorbent resin which is suitable for commercial production.